Request for Help – Flashing Della Minisplit WiFi Module (WBR3 on TCWBRCU1)

dressyspider 3684 211

#211 21597558 04 Jul 2025 16:25

p.kaczmarek2 p.kaczmarek2

Moderator Smart Home

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Post #211
21597558 04 Jul 2025 16:25

That's good to hear. Do you have any suggestions for potential improvements of this driver?

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

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#212 21598454 05 Jul 2025 20:32

AbidingOhmsLaw AbidingOhmsLaw

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Post #212
21598454 05 Jul 2025 20:32

>>21597558 Not at this time, not with the driver anyway, hell the few issues I have are with the Della itself, the remotes are IR so only one way communication. OpenBeken and the Driver has been working awesomely and I can access all the needed functionality with the climate card is HA. I have not tried heat mode but would not expect any issues.
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Topic summary

The discussion centers on flashing and customizing the WiFi module (WBR3 on TCWBRCU1 board) of a Della Optima Series minisplit air conditioner to run OpenBeken firmware for local, cloud-free control. Initial assumptions about the device using TuyaMCU were revised after UART traffic analysis revealed a custom protocol similar to TCL AC units, leading to the development and testing of a dedicated TCL driver in OpenBeken. The user successfully desoldered the WBR3 module, backed up its firmware using appropriate Realtek tools (ltchiptool and AmebaZ2 PG Tool), and flashed OpenBeken firmware. Key datapoints such as power, mode, fan speed, temperature, humidity, and PM2.5 were identified from the Tuya IoT platform, but the device uses a binary packet protocol rather than standard Tuya DPIDs.

The community collaboratively developed and refined the TCL driver, enabling control of power, mode (cool, heat, dry, fan, auto), fan speeds (mapped to Smart Life app presets including auto, mute, mid-low to turbo), swing positions (vertical and horizontal), buzzer (beep) on/off, and display brightness on/off. The driver was integrated with Home Assistant via MQTT with discovery support, allowing control and state feedback. Challenges included correct UART parity settings (even parity), packet parsing, and mapping driver values to Home Assistant entities. The user provided detailed logs, testing results, and UI feedback, leading to improvements in MQTT integration, UI elements for fan speed and swing controls, and bug fixes for state synchronization. The project also discussed future enhancements like better OBK UI integration, thermostat card improvements, and potential DIY thermostat projects using OBK on ESP32 with external sensors.

Overall, the thread documents a successful reverse engineering and firmware replacement effort for the Della minisplit WiFi module, enabling local control with OpenBeken, full MQTT/Home Assistant integration, and detailed community-driven driver development for a non-standard protocol device.
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FAQ

TL;DR: Flash the Della TCWBRCU1/WBR3 Wi-Fi dongle over 3 V3 UART (9600 8E1) with AmebaZ2 PG Tool, then load the current OpenBeken build and start the new TCL driver to keep full HVAC control locally. Keep target temps between 16-31 °C (0-15 protocol value) and back up the 2 MB SPI flash first [Elektroda, dressyspider, #21544728].

Quick Facts

• MCU / RF : Realtek RTL8710BN (AmebaZ2) on WBR3 [WBR3 Datasheet]
• Flash size: 2 MB (0x200000) dump confirmed [Elektroda, divadiow, #21544743]
• UART port : 9600 bps, 8 data, **Even** parity, 1 stop [Elektroda, p.kaczmarek2, #21550462]
• Protocol : 0xBB header, 61-byte TCL packet; temp field = (°C-16) (4 bits) [Elektroda, p.kaczmarek2, #21552449]
• Product ID: klo4xmr94giahmug (Tuya Cat. kt) [Elektroda, dressyspider, #21552194]

How do I back up the factory firmware before flashing?

Solder RX, TX, GND, 3 V3 and EN to the six WBR3 pads, short EN to GND, run AmebaZ2 PG Tool and click "Read Flash". The tool saves a 0x200000-byte BIN that can be restored later [Elektroda, divadiow, #21544726].

Which OpenBeken binary should I upload?

Use the artefact file OpenRTL87X0C_x.xx.xx.bin from the latest CI build or PR #1650; upload with PG Tool’s "Write Flash" then reboot [Elektroda, p.kaczmarek2, #21559301].

How do I start the new TCL driver?

After Wi-Fi connects, issue the command startDriver TCL. OBK adds runtime commands such as ACMode, TargetTemperature, FANMode, SwingH, SwingV, Buzzer and Display [Elektroda, p.kaczmarek2, #21550113].

What ACMode numbers map to the unit’s modes?

0 = Off, 1 = Cool, 2 = Dry, 3 = Fan-only, 4 = Heat, 5 = Heat-Cool, 6 = Auto [Elektroda, p.kaczmarek2, #21550217].

Why does TargetTemperature 75 show 81 °F on the wall unit?

OBK currently expects Celsius. Internally the packet stores (°C-16), so send 24 → 75 °F or 25 → 77 °F. The wall display uses Fahrenheit when DP 19 = “f” [Elektroda, p.kaczmarek2, #21553236].

How can I silence the confirmation beep?

Run Buzzer 0 to clear the sound-bit; Buzzer 1 re-enables it. The command toggles bit 3 of byte 0x19 in the TCL packet [Elektroda, p.kaczmarek2, #21559301].

Can I turn off the bright LED display?

Yes. Display 0 switches off the segment LEDs; Display 1 turns them on. Added in PR #1650 [Elektroda, p.kaczmarek2, #21559501].

What fan-speed values are valid?

FANMode 0-7 follow Tuya list: 0-auto, 1-low, 2-mid-low, 3-mid, 4-mid-high, 5-high, 6-strong, 7-mute (extra-slow) [Elektroda, dressyspider, #21536711].

How do I expose the AC in Home Assistant?

Enable MQTT in OBK, set topic prefix (e.g. "Mini Split"). OBK publishes • state → <prefix>/event/cooling/state • target temp → <prefix>/event/cooling/target Send commands to <prefix>/cmnd/TargetTemperature, ACMode, etc. Home Assistant’s MQTT Climate platform can map these fields [OpenBeken Docs].

Is the UART parity the same on replacement modules like WB3S?

Yes—Tuya WB3S, CB3S and TYWE3S break out the same 6-pin UART; all support 8E1 at 9600 bps when running OBK [Elektroda, p.kaczmarek2, #21548807].

Can I still revert to Tuya Cloud after flashing?

If you saved the full 2 MB dump, write it back with PG Tool and re-pair in the Smart Life app. Keep the original WBR3 dongle as a fallback [Elektroda, dressyspider, #21541593].

Does the driver read indoor and outdoor temperatures?

It currently parses DP 3 (indoor) and DP 23 (indoor°F). Outdoor sensor data isn’t exposed by the TCL MCU packet, so OBK cannot show it [Elektroda, p.kaczmarek2, #21552449].

Where are the UART pins on the TCWBRCU1 board?

The six vias under the USB tongue map left-to-right to 3 V3, RX, TX, EN, IO0, GND. They align with A0, A1, A15 test pads shown in the teardown images [Elektroda, dressyspider, #21536655].

What happens if I flash with wrong parity?

The module boots but the TCL MCU never recognises packets, so no relay, fan or temperature control respond [Elektroda, insmod, #21550485].

Is there a risk of over-current on the 3 V3 rail?

The WBR3 draws approx. 120 mA peak during TX [WBR3 Datasheet]. A typical USB-A port on the indoor PCB can supply 500 mA, so flashing and runtime remain within safe limits.